This type of coupling link is described in German patent document No. 31 49 700.
According to this document, it is known that the effective point of attachment of a coupling link between towing vehicle and trailer can be transferred from the normal flank position at the towing vehicle in the direction of the center of gravity of said towing vehicle. This can be achieved by means of angular steering arms, which, on the one hand, are pivoted at the towing vehicle and, on the other hand, at the trailer, with varying distances from one another, thus replacing the generally used towing fork. The fulcrum points at the towing vehicle lie in closer proximity to one another than those at the trailer. In theory, this permits the possibility of steering the towing vehicle opposite the longitudinal axis of the trailer up to a 60.degree. angle, and the pitching motion occurring with the towing vehicle and trailer can, therefore, be reduced considerably.
There are, nevertheless, a number of problems with this design, especially with respect to the strength requirements, which have proved to be necessary for standard tests, vehicle registration inspections and road behavior when the vehicle is in turning position.